U.S. patent application number 15/333142 was filed with the patent office on 2017-02-16 for distance measurement device, distance measurement method, and distance measurement program.
The applicant listed for this patent is FUJIFILM CORPORATION. Invention is credited to Tomonori MASUDA, Hiroshi TAMAYAMA.
Application Number | 20170048459 15/333142 |
Document ID | / |
Family ID | 54358454 |
Filed Date | 2017-02-16 |
United States Patent
Application |
20170048459 |
Kind Code |
A1 |
MASUDA; Tomonori ; et
al. |
February 16, 2017 |
DISTANCE MEASUREMENT DEVICE, DISTANCE MEASUREMENT METHOD, AND
DISTANCE MEASUREMENT PROGRAM
Abstract
A distance measurement device includes an imaging optical
system, an imaging unit, an emission unit, a derivation unit which
performs a distance measurement to derive a distance to a subject
based on a timing at which directional light is emitted by the
emission unit and a timing at which reflected light is received by
a light receiving unit, a shake correction unit which performs
shake correction as correction of shake of the subject image caused
by variation of an optical axis of the imaging optical system, and
a control unit which performs control such that the shake
correction unit does not perform shake correction or performs shake
correction with a correction amount smaller than a normal
correction amount determined in advance in a case of performing the
distance measurement and performs shake correction with the normal
correction amount in a case of not performing the distance
measurement.
Inventors: |
MASUDA; Tomonori; (Saitama,
JP) ; TAMAYAMA; Hiroshi; (Saitama, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJIFILM CORPORATION |
Tokyo |
|
JP |
|
|
Family ID: |
54358454 |
Appl. No.: |
15/333142 |
Filed: |
October 24, 2016 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2015/056875 |
Mar 9, 2015 |
|
|
|
15333142 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03B 2205/0023 20130101;
H04N 5/232123 20180801; H04N 5/23212 20130101; H04N 5/2256
20130101; G01S 17/89 20130101; G03B 17/20 20130101; G03B 13/36
20130101; H04N 5/23267 20130101; H04N 5/2353 20130101; H04N
5/232945 20180801; H04N 5/2351 20130101; G01C 3/06 20130101; G01C
3/08 20130101; G01S 17/10 20130101; H04N 5/23258 20130101 |
International
Class: |
H04N 5/232 20060101
H04N005/232; H04N 5/235 20060101 H04N005/235; G01S 17/89 20060101
G01S017/89; H04N 5/225 20060101 H04N005/225; G01C 3/08 20060101
G01C003/08; G01S 17/10 20060101 G01S017/10 |
Foreign Application Data
Date |
Code |
Application Number |
May 2, 2014 |
JP |
2014-095556 |
Aug 5, 2014 |
JP |
2014-159806 |
Claims
1. A distance measurement device comprising: an imaging optical
system which forms a subject image indicating a subject; an imaging
unit which captures the subject image formed by the imaging optical
system; an emission unit which emits directional light as light
having directivity along an optical axis direction of the imaging
optical system; a light receiving unit which receives reflected
light of the directional light from the subj ect; a derivation unit
which performs a distance measurement to derive a distance to the
subject based on a timing at which the directional light is emitted
by the emission unit and a timing at which the reflected light is
received by the light receiving unit; a shake correction unit which
performs shake correction as correction of shake of the subject
image caused by variation of the optical axis of the imaging
optical system; and a control unit which performs control such that
the shake correction unit does not perform the shake correction, or
performs the shake correction with a correction amount smaller than
a normal correction amount determined in advance in a case of
performing a distance measurement operation relating to the
distance measurement and synchronously performing an imaging
operation for a still image by the imaging unit, and performs the
shake correction with the normal correction amount in a case of
performing the imaging operation without performing the distance
measurement operation.
2. The distance measurement device according to claim 1, further
comprising: a reception unit which receives an input of an
instruction regarding whether or not to perform the distance
measurement by the emission unit, the light receiving unit, and the
derivation unit, wherein the control unit performs control such
that the shake correction unit does not perform the shake
correction or performs the shake correction with a correction
amount smaller than a normal correction amount determined in
advance, in a case where an input of an instruction to perform the
distance measurement is received by the reception unit and performs
the shake correction with the normal correction amount in a case
where an input of an instruction not to perform the distance
measurement is received by the reception unit.
3. The distance measurement device according to claim 1, further
comprising: a detection unit which detects the shake, wherein the
shake correction unit calculates a correction amount for correcting
the shake based on a detection result of the detection unit, and
the control unit calculates an irradiation position of the
directional light irradiated from the emission unit based on the
calculated correction amount and displays a marker representing the
calculated irradiation position on a display unit.
4. The distance measurement device according to claim 3, wherein
the control unit controls the size of the marker representing the
irradiation position based on the calculated correction amount.
5. The distance measurement device according to claim 1, wherein
the derivation unit performs the derivation of the distance
multiple times and derives a distance having a high frequency among
the distances obtained by deriving the distance multiple times as a
final distance.
6. The distance measurement device according to claim 5, further
comprising: an execution unit which executes at least one of focus
adjustment of the imaging optical system with respect to the
subject or exposure adjustment, wherein, in a case where the
execution unit executes the focus adjustment, and in a case of
deriving the distance, the derivation unit determines a distance
range for use when determining the frequency or a time range from
the emission of the directional light to the reception of the
directional light based on focusing state specification information
and derives the final distance within the determined distance range
or the determined time range.
7. The distance measurement device according to claim 6, wherein,
in a case of deriving the distance, the derivation unit derives the
final distance with a resolution determined according to a result
of determination of the distance range or the time range.
8. The distance measurement device according to claim 1, wherein
the emission unit is able to adjust the emission intensity of the
directional light and adjusts the emission intensity based on at
least one of focusing state specification information and subject
brightness or exposure state specification information to emit the
directional light.
9. The distance measurement device according to claim 8, wherein
the emission unit makes the emission intensity lower when a focal
distance indicated by the focusing state specification information
is shorter.
10. The distance measurement device according to claim 8, wherein
the emission unit makes the emission intensity lower when the
subject brightness is lower and makes the emission intensity lower
when the exposure indicated by the exposure state specification
information is higher.
11. The distance measurement device according to claim 1, wherein
the light receiving unit is able to adjust light receiving
sensitivity and adjusts the light receiving sensitivity based on
focusing state specification information to receive the reflected
light.
12. The distance measurement device according to claim 11, wherein
the light receiving unit makes the light receiving sensitivity
lower when a focal distance indicated by the focusing state
specification information is shorter.
13. The distance measurement device according to claim 1, further
comprising: a display unit which displays an image, wherein the
control unit performs control such that the display unit displays a
motion image captured by the imaging unit and displays information
relating to the distance to the subject derived by the derivation
unit.
14. The distance measurement device according to claim 1, wherein a
distance measurement by the emission unit, the light receiving
unit, and the derivation unit is performed a number of times
determined in advance according to subject brightness or exposure
state specification information.
15. The distance measurement device according to claim 14, wherein
a distance measurement by the emission unit, the light receiving
unit, and the derivation unit is performed a larger number of times
when the subject brightness is higher or when the exposure
indicated by the exposure state specification information is
lower.
16. The distance measurement device according to claim 1, further
comprising: a storage unit which stores the distance derived by the
derivation unit, wherein storage by the storage unit is stopped in
a case where the derivation of the distance by the derivation unit
is impossible.
17. The distance measurement device according to claim 16, further
comprising: a storage setting unit which sets whether or not to
stop storage by the storage unit in a case where the derivation of
the distance by the derivation unit is impossible.
18. The distance measurement device according to claim 1, wherein
the derivation unit derives the distance in a case where there is
no focus adjustment error by a focus adjustment unit performing
focus adjustment of the imaging optical system with respect to the
subject and there is no exposure adjustment error by an exposure
adjustment unit adjusting exposure in a case where the imaging unit
performs imaging.
19. A distance measurement method comprising: performing a distance
measurement to derive a distance to a subject based on a timing at
which directional light is emitted by an emission unit emitting the
directional light as light having directivity along an optical axis
direction of an imaging optical system forming a subject image
indicating the subject, and a timing at which reflected light is
received by a light receiving unit receiving the reflected light of
the directional light from the subject; and performing control such
that a shake correction unit does not perform shake correction as
correction of shake of the subject image caused by variation of the
optical axis of the imaging optical system, or performs the shake
correction with a correction amount smaller than a normal
correction amount determined in advance, in a case of performing a
distance measurement operation relating to the distance measurement
and synchronously performing an imaging operation that captures the
subject image formed by the imaging optical system as a still
image, and the imaging operation, and performs the shake correction
with the normal correction amount in a case of performing the
imaging operation without performing the distance measurement
operation.
20. A non-transitory computer-readable storage medium storing a
distance measurement program for causes a computer to execute
processing comprising: performing a distance measurement to derive
a distance to a subject based on a timing at which directional
light is emitted by an emission unit emitting the directional light
as light having directivity along an optical axis direction of an
imaging optical system forming a subject image indicating the
subject, and a timing at which reflected light is received by a
light receiving unit receiving the reflected light of the
directional light from the subject; and performing control such
that a shake correction unit does not perform shake correction as
correction of shake of the subject image caused by variation of the
optical axis of the imaging optical system, or performs the shake
correction with a correction amount smaller than a normal
correction amount determined in advance, in a case of performing a
distance measurement operation relating to the distance measurement
and synchronously performing an imaging operation that captures the
subject image formed by the imaging optical system as a still
image, and the imaging operation, and performs the shake correction
with the normal correction amount in a case of performing the
imaging operation without performing the distance measurement
operation.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of
International Application No. PCT/JP2015/056875, filed Mar. 9,
2015, the disclosure of which is incorporated herein by reference
in its entirety. Further, this application claims priority from
Japanese Patent Application No. 2014-095556, filed May 2, 2014, and
Japanese Patent Application No. 2014-159806, filed Aug. 5, 2014,
the disclosures of which are incorporated herein by reference in
their entireties.
BACKGROUND
[0002] 1. Technical Field
[0003] A technique of the present disclosure relates to a distance
measurement device, a distance measurement method, and a distance
measurement program.
[0004] 2. Related Art
[0005] JP2008-96181A discloses a device including time detection
means for detecting the time from the emission of measurement light
to the reception of measurement light by light receiving means,
shake amount detection means for detecting a shake amount of a
housing during emission of measurement light when measurement light
is emitted from light emitting means, and distance determination
means for determining the distance to an object to be measured
based on the time detected by the time detection means and the
shake amount detected by the shake amount detection means.
[0006] JP2002-207163A discloses a distance measurement and imaging
device having a function of performing focus adjustment, a distance
measurement function of measuring a distance to a subject by
irradiating the subject with a laser beam along an optical axis of
a lens and detecting reflected light of the laser beam, and an
imaging function of imaging the subject.
SUMMARY
[0007] On the other hand, typically, in a case where a distance
measurement is performed by a distance measurement device, the
distance measurement device is used in a state of being held by a
user. In this state, if a phenomenon in which the vibration of the
hand of the user is transmitted to cause the vibration of the
distance measurement device, that is, camera shake, occurs, an
optical axis of an imaging optical system included in the distance
measurement device varies with camera shake. In a case where the
distance measurement device is mounted in a vehicle, the vibration
of the vehicle may be transmitted to cause the vibration of the
distance measurement device and the optical axis of the imaging
optical system may vary. Here, the variation of the optical axis
means that the optical axis is inclined with respect to a reference
axis (for example, an optical axis before camera shake occurs).
[0008] In this way, if the optical axis of the imaging optical
system varies, image shake or image blur (hereinafter, in a case
where there is no need for distinction, referred to as "shake")
occurs. "Image shake" indicates, for example, a phenomenon in which
a subject image is deviated from a reference position (for example,
the position of the subject image obtained in a state where image
shake does not occur) with variation of the optical axis of the
imaging optical system included in the distance measurement device.
"Image blur" indicates, for example, a phenomenon in which an image
obtained by imaging is deviated from a reference position with the
relative movement of the optical axis with respect to the subject
due to camera shake or the like.
[0009] In the technique of the related art, in a case of performing
correction (shake correction) of shake, the position of the subject
image formed on the imaging unit may vary, and in this case, if a
distance measurement is performed, there is a concern that distance
measurement accuracy is degraded.
[0010] An embodiment of the invention has been suggested in
consideration of such a situation, and provides a distance
measurement device, a distance measurement method, and a distance
measurement program capable of suppressing degradation of distance
measurement accuracy due to shake correction.
[0011] In order to attain the above-described object, a distance
measurement device according to a first aspect of the invention
comprises an imaging optical system which forms a subject image
indicating a subject, an imaging unit which captures the subject
image formed by the imaging optical system, an emission unit which
emits directional light as light having directivity along an
optical axis direction of the imaging optical system, a light
receiving unit which receives reflected light of the directional
light from the subject, a derivation unit which performs a distance
measurement to derive a distance to the subject based on a timing
at which the directional light is emitted by the emission unit and
a timing at which the reflected light is received by the light
receiving unit, a shake correction unit which performs shake
correction as correction of shake of the subject image caused by
variation of the optical axis of the imaging optical system, and a
control unit which performs control such that the shake correction
unit does not perform the shake correction or performs the shake
correction with a correction amount smaller than a normal
correction amount determined in advance in a case of performing the
distance measurement and performs the shake correction with the
normal correction amount in a case of not performing the distance
measurement.
[0012] According to a second aspect of the invention, the distance
measurement device according to the first aspect of the invention
may further comprise a reception unit which receives an input of an
instruction regarding whether or not to perform the distance
measurement by the emission unit, the light receiving unit, and the
derivation unit, and the control unit may perform control such that
the shake correction unit does not perform the shake correction or
performs the shake correction with a correction amount smaller than
a normal correction amount determined in advance in a case where an
input of an instruction to perform the distance measurement is
received by the reception unit and performs the shake correction
with the normal correction amount in a case where an input of an
instruction not to perform the distance measurement is received by
the reception unit.
[0013] According to a third aspect of the invention, the distance
measurement device according to the first or second aspect of the
invention may further comprise a detection unit which detects the
shake, the shake correction unit may calculate a correction amount
for correcting the shake based on a detection result of the
detection unit, and the control unit may calculate an irradiation
position of the directional light irradiated from the emission unit
based on the calculated correction amount and may display a marker
representing the calculated irradiation position on a display
unit.
[0014] According to a fourth aspect of the invention, in the
distance measurement device according to the third aspect of the
invention, the control unit controls the size of the mark
representing the irradiation position based on the calculated
correction amount.
[0015] According to a fifth aspect of the invention, in the
distance measurement device according to any one of the first to
fourth aspects of the invention, the derivation unit may perform
the derivation of the distance multiple times and may derive a
distance having a high frequency among the distances obtained by
deriving the distance multiple times as a final distance.
[0016] According to a sixth aspect of the invention, the distance
measurement device according to the fifth aspect of the invention
may further comprise an execution unit which executes at least one
of focus adjustment of the imaging optical system with respect to
the subject or exposure adjustment, and in a case where the
execution unit executes the focus adjustment, and in a case of
deriving the distance, the derivation unit may determine a distance
range for use when determining the frequency or a time range from
the emission of the directional light to the reception of the
directional light based on focusing state specification information
and may derive the final distance within the determined distance
range or the determined time range.
[0017] According to a seventh aspect of the invention, in the
distance measurement device according to the sixth aspect of the
invention, in a case of deriving the distance, the derivation unit
may derive the final distance with a resolution determined
according to a result of determination of the distance range or the
time range.
[0018] According to an eighth aspect of the invention, in the
distance measurement device according to any one of the first to
seventh aspects of the invention, the emission unit may be able to
adjust the emission intensity of the directional light and may
adjust the emission intensity based on at least one of focusing
state specification information and subject brightness or exposure
state specification information to emit the directional light.
[0019] According to a ninth aspect of the invention, in the
distance measurement device according to the eighth aspect of the
invention, the emission unit may make the emission intensity lower
when a focal distance indicated by the focusing state specification
information is shorter.
[0020] According to a tenth aspect of the invention, in the
distance measurement device according to the eighth or ninth aspect
of the invention, the emission unit may make the emission intensity
lower when the subject brightness is lower and may make the
emission intensity lower when the exposure indicated by the
exposure state specification information is higher.
[0021] According to an eleventh aspect of the invention, in the
distance measurement device according to any one of the first to
tenth aspects of the invention, the light receiving unit may be
able to adjust light receiving sensitivity and may adjust the light
receiving sensitivity based on focusing state specification
information to receive the reflected light.
[0022] According to a twelfth aspect of the invention, in the
distance measurement device according to the eleventh aspect of the
invention, the light receiving unit may make the light receiving
sensitivity lower when a focal distance indicated by the focusing
state specification information is shorter.
[0023] According to a thirteenth aspect of the invention, the
distance measurement device according to any one of the first to
twelfth aspects of the invention may further comprise a display
unit which displays an image, and the control unit may perform
control such that the display unit displays a motion image captured
by the imaging unit and displays information relating to the
distance to the subject derived by the derivation unit.
[0024] According to a fourteenth aspect of the invention, in the
distance measurement device according to any one of the first to
thirteenth aspects of the invention, a distance measurement by the
emission unit, the light receiving unit, and the derivation unit
may be performed a number of times determined in advance according
to subject brightness or exposure state specification information.
With this, the distance measurement device of the fourteenth aspect
can obtain a distance measurement result, in which the influence of
noise of ambient light is moderated, compared to a case where the
light emission frequency of directional light is fixed regardless
of subject brightness.
[0025] According to a fifteenth aspect of the invention, in the
distance measurement device according to the fourteenth aspect of
the invention, a distance measurement by the emission unit, the
light receiving unit, and the derivation unit may be performed a
larger number of times when the subject brightness is higher or
when the exposure indicated by the exposure state specification
information is lower. With this, the distance measurement device
according to the fifteenth aspect of the invention can obtain a
distance measurement result, in which the influence of noise of
ambient light is moderated, compared to a case where the light
emission frequency of directional light is fixed regardless of high
subject brightness.
[0026] According to a sixteenth aspect of the invention, the
distance measurement device according to any one of the first to
fifteenth aspects of the invention may further comprise a storage
unit which stores the distance derived by the derivation unit, and
storage by the storage unit may be stopped in a case where the
derivation of the distance by the derivation unit is impossible.
With this, the distance measurement device according to the
sixteenth aspect of the invention can prevent storage of incomplete
distance data.
[0027] According to a seventeenth aspect of the invention, the
distance measurement device according to the sixteenth aspect of
the invention may further comprise a storage setting unit which
sets whether or not to stop storage by the storage unit in a case
where the derivation of the distance by the derivation unit is
impossible. With this, the distance measurement device according to
the seventeenth aspect of the invention can set whether or not to
perform storage into the storage unit according to a user's
intention in a case where the derivation of the distance is
impossible.
[0028] According to an eighteenth aspect of the invention, in the
distance measurement device according to any one of the first to
seventeenth aspects of the invention, the derivation unit may
derive the distance in a case where there is no focus adjustment
error by a focus adjustment unit performing focus adjustment of the
imaging optical system with respect to the subject and there is no
exposure adjustment error by an exposure adjustment unit adjusting
exposure in a case where the imaging unit performs imaging. With
this, the distance measurement device according to the eighteenth
aspect of the invention can obtain a distance measurement result
along with an image subjected to focusing and exposure
adjustment.
[0029] A distance measurement method according to a nineteenth
aspect of the invention comprises performing a distance measurement
to derive a distance to a subject based on a timing at which
directional light is emitted by an emission unit emitting
directional light as light having directivity along an optical axis
direction of an imaging optical system forming a subject image
indicating the subject and a timing at which reflected light is
received by a light receiving unit receiving the reflected light of
the directional light from the subject, and performing control such
that a shake correction unit does not perform shake correction as
correction of shake of the subject image caused by variation of the
optical axis of the imaging optical system or performs the shake
correction with a correction amount smaller than a normal
correction amount determined in advance in a case of performing the
distance measurement and performs the shake correction with the
normal correction amount in a case of not performing the distance
measurement.
[0030] A distance measurement program according to a twentieth
aspect of the invention causes a computer to execute processing
including performing a distance measurement to derive a distance to
a subject based on a timing at which directional light is emitted
by an emission unit emitting directional light as light having
directivity along an optical axis direction of an imaging optical
system forming a subject image indicating the subject and a timing
at which reflected light is received by a light receiving unit
receiving the reflected light of the directional light from the
subject, and performing control such that a shake correction unit
does not perform shake correction as correction of shake of the
subject image caused by variation of the optical axis of the
imaging optical system or performs the shake correction with a
correction amount smaller than a normal correction amount
determined in advance in a case of performing the distance
measurement and performs the shake correction with the normal
correction amount in a case of not performing the distance
measurement.
[0031] According to an embodiment of the invention, it is possible
to suppress degradation of distance measurement accuracy due to
shake correction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Exemplary embodiments according to the technique of the
present disclosure will be described in detail based on the
following figures, wherein:
[0033] FIG. 1 is a block diagram showing an example of the
configuration of a main part of a distance measurement device
according to this embodiment;
[0034] FIG. 2 is a timing chart showing an example of a timing of a
distance measurement operation to measure a distance to a subject
in the distance measurement device according to this
embodiment;
[0035] FIG. 3 is a timing chart showing an example of a timing from
light emission to light reception in a single measurement in the
distance measurement device of the first embodiment;
[0036] FIG. 4 is a graph showing an example of a histogram of
measured values in a case where a distance to a subject is set as a
horizontal axis and a measurement frequency is set as a vertical
axis;
[0037] FIG. 5 is a flowchart showing an example of a flow of
control processing which is executed by a main control unit of the
distance measurement device according to this embodiment;
[0038] FIG. 6 is an example of a timing chart showing the timings
of an imaging operation and a distance measurement operation in the
distance measurement device according to this embodiment;
[0039] FIG. 7 is a flowchart showing an example of distance
measurement processing which is executed by a distance measurement
control unit of the distance measurement device according to this
embodiment;
[0040] FIG. 8 is a flowchart showing another example of a flow of
control processing which is executed by the main control unit of
the distance measurement device according to this embodiment;
[0041] FIG. 9 is a flowchart showing another example of a flow of
control processing which is executed by the main control unit of
the distance measurement device according to this embodiment;
[0042] FIG. 10A is a diagram illustrating a marker representing an
irradiation position which is displayed on a live view image of a
view finder in a superimposed manner;
[0043] FIG. 10B is a conceptual diagram showing an example of a
marker which represents an irradiation position displayed on a live
view image of a view finder in a superimposed manner and is
displayed large;
[0044] FIG. 10C is a conceptual diagram showing an example of a
marker which represents an irradiation position displayed on a live
view image of a view finder in a superimposed manner and is
displayed small;
[0045] FIG. 11A is a modification example of a histogram obtained
in the distance measurement device according to the embodiment, and
is a diagram illustrating an example of deriving a distance to a
subject without using a measurement result other than a subject
distance range based on AF;
[0046] FIG. 11B is a modification example of a histogram obtained
in the distance measurement device according to the embodiment, and
is a diagram illustrating an example of deriving a distance to a
subject without using a measured value of a distance less than a
subject distance based on AF;
[0047] FIG. 11C is a modification example of a histogram obtained
in the distance measurement device according to the embodiment, and
is a diagram illustrating an example of deriving a distance to a
subject without using a measured value of a distance longer than a
subject distance based on AF;
[0048] FIG. 12 is an explanatory view illustrating adjustment of
emission intensity of a laser beam or light receiving sensitivity
of a photodiode based on an AF result or an AE result;
[0049] FIG. 13 is another example of a timing chart representing
the timings of an imaging operation and a distance measurement
operation in the distance measurement device according to this
embodiment;
[0050] FIG. 14 is a conceptual diagram showing an example of the
configuration of a light emission frequency determination
table;
[0051] FIG. 15 is a flowchart showing an example of a flow of
brightness information transmission processing;
[0052] FIG. 16 is a flowchart showing an example of a flow of light
emission frequency determination processing;
[0053] FIG. 17 is a conceptual diagram showing another example of
the configuration of a light emission frequency determination
table;
[0054] FIG. 18 is a flowchart showing another example of a flow of
exposure state specification information transmission processing;
and
[0055] FIG. 19 is a flowchart showing another example of a flow of
light emission frequency determination processing.
DETAILED DESCRIPTION
[0056] Hereinafter, an example of an embodiment of a distance
measurement device according to the technique of the present
disclosure will be described referring to the accompanying
drawings. In this embodiment, a "distance measurement" indicates a
measurement of a distance to a subject to be a measurement
target.
[0057] First, the configuration of the distance measurement device
according to this embodiment will be described. FIG. 1 is a block
diagram showing the configuration of a main part of a distance
measurement device 10 according to this embodiment.
[0058] The distance measurement device 10 of this embodiment has a
function of performing a distance measurement and a function of
generating a captured image obtained by imaging a subject. The
distance measurement device 10 of this embodiment comprises a
control unit 20, a light emitting lens 30, a laser diode 32, a
light receiving lens 34, a photodiode 36, an imaging optical system
40, an imaging element 42, an operating unit 44, a view finder 46,
and a storage unit 48.
[0059] The control unit 20 comprises a time counter 22, a distance
measurement control unit 24, and a main control unit 26. The time
counter 22 has a function of generating a count signal in each
given period determined in advance according to a signal (for
example, a clock pulse) input from the main control unit 26 through
the distance measurement control unit 24.
[0060] The distance measurement control unit 24 has a function of
performing a distance measurement under the control of the main
control unit 26. The distance measurement control unit 24 of this
embodiment controls the driving of the laser diode 32 at a timing
according to the count signal generated by the time counter 22 to
perform the distance measurement. The distance measurement control
unit 24 functions as a derivation unit according to the technique
of the present disclosure. Specific implementation examples of the
distance measurement control unit 24 include an application
specific integrated circuit (ASIC), a field-programmable gate array
(FPGA), and the like. The distance measurement control unit 24 of
this embodiment has a storage unit (not shown). Specific examples
of the storage unit in the distance measurement control unit 24
include a nonvolatile storage unit, such as a read only memory
(ROM), and a volatile storage unit, such as a random access memory
(RAM).
[0061] The main control unit 26 has a function of controlling the
entire distance measurement device 10. The main control unit 26 of
this embodiment has a function of controlling the imaging optical
system 40 and the imaging element 42 to image a subject and
generating a captured image (subject image). The main control unit
26 functions as a control unit, a shake correction unit, a
brightness detection unit, a focus adjustment unit, and an exposure
adjustment unit according to the technique of the present
disclosure. Specific examples of the main control unit 26 include a
central processing unit (CPU) and the like. The distance
measurement control unit 24 of this embodiment has a storage unit
(not shown). Specific examples of the storage unit in the distance
measurement control unit 24 include a nonvolatile storage unit,
such as a ROM, and a volatile storage unit, such as a RAM. A
control program described below is stored in the ROM in
advance.
[0062] The main control unit 26 of this embodiment has a function
of performing correction (shake correction) of shake. The term
"shake" used herein indicates, for example, image shake or image
blur accompanied by a phenomenon (camera shake) in which the
vibration of the hand of the user is transmitted to cause the
vibration of the distance measurement device 10, a phenomenon in
which the vibration of a vehicle is transmitted to the distance
measurement device 10 mounted in the vehicle (not shown) to cause
the vibration of the distance measurement device 10, or the like.
The term "image shake" indicates, for example, a phenomenon in
which a subject image is deviated from a reference position (for
example, the position of the subject image obtained in a state
where camera shake does not occur) with variation of the optical
axis of the imaging optical system 40. Furthermore, "image blur"
indicates, for example, a phenomenon in which an image obtained by
imaging is deviated from a reference position with relative
movement of the optical axis of the imaging optical system 40 with
respect to the subject due to camera shake or the like. The main
control unit 26 of this embodiment performs shake correction of a
so-called CCD shift system. The main control unit 26 performs shake
correction based on a detection result of the shake detection unit
43 by moving the imaging element 42 and adjusting a subject image
to be formed on the imaging element 42 in a case where shake
occurs. In this embodiment, the user can operate the operating unit
44 to select whether or not to perform shake correction. A system
of shake correction is not limited to a CCD shift system, and other
general systems (for example, lens shift system shake correction in
which a vibration-proof lens (not shown) included in the imaging
optical system 40 varies according to a detection result of the
shake detection unit 43, electronic correction processing of
correcting image blur by processing an image signal obtained by
imaging, and the like) may be applied. In this embodiment, "shake
correction" includes a meaning of reduction in shake, in addition
to a meaning of elimination of shake.
[0063] A program of control processing is not necessarily stored in
the main control unit 26 from the beginning. For example, a control
program may be stored in advance in an arbitrary portable storage
medium, such as a solid state drive (SSD), a CD-ROM, a DVD, a
magneto-optical disk, or an IC card. The distance measurement
device 10 may acquire the control program from the portable storage
medium storing the control program and may store the control
program in the main control unit 26 or the like. Furthermore, the
distance measurement device 10 may acquire the control program from
other external devices through the Internet or a local area network
(LAN) and may store the control program in the main control unit 26
or the like.
[0064] The operating unit 44 is a user interface which is operated
by the user when various instructions are provided to the distance
measurement device 10. The operating unit 44 includes a release
button, a distance measurement instruction button, and buttons,
keys, or the like (all of these are not shown) which are used when
the user provides various instructions. Various instructions
received by the operating unit 44 are output to the main control
unit 26 as operation signals, and the main control unit 26 executes
processing according to the operation signals input from the
operating unit 44. The operating unit 44 is an example of a
reception unit according to the technique of the present
disclosure.
[0065] The shake detection unit 43 has a function of detecting
shake, and comprises, for example, a sensor, such as a gyro
sensor.
[0066] The release button of the operating unit 44 detects a
two-stage pressing operation of an imaging preparation instruction
state and an imaging instruction state. The imaging preparation
instruction state indicates, for example, a state of being pressed
from a standby position to an intermediate position (half-pressing
position), and the imaging instruction state indicates a state of
being pressed to a final pressing position (fully pressing
position) beyond the intermediate position. Hereinafter, "the state
of being pressed from the standby position to the half-pressing
position" refers to a "half-pressing state", and "the state of
being pressed from the standby position to the fully pressing
position" refers to a "fully pressing state".
[0067] In the distance measurement device 10 according to this
embodiment, a manual focus mode and an auto-focus mode are
selectively set according to a user's instruction. In the
auto-focus mode, adjustment of imaging conditions is performed by
bringing the release button of the operating unit 44 into the
half-pressing state, and then, exposure (imaging) is performed by
successively bringing the release button into the fully pressing
state. That is, if the release button of the operating unit 44 is
brought into the half-pressing state, an automatic exposure (AE)
function is operated to perform exposure adjustment, and an
auto-focus (AF) function is operated to perform focusing control,
and if the release button is brought into the fully pressing state,
imaging is performed.
[0068] In this embodiment, the main control unit 26 transmits
exposure state specification information for specifying an exposure
state at the present time as a result of AE to the distance
measurement control unit 24. The main control unit 26 transmits
focusing state specification information for specifying a focusing
state at the present time as a result of AF to the distance
measurement control unit 24. Examples of the exposure state
specification information include an F-number and a shutter speed
derived from a so-called AE evaluation value uniquely determined
according to subject brightness. Other examples of the exposure
state specification information include an AE evaluation value.
Examples of the focusing state specification information include
the subject distance obtained by AF.
[0069] The storage unit 48 primarily stores image data obtained by
imaging, and a nonvolatile memory is used therefor. Specific
examples of the storage unit 48 include a flash memory or a hard
disk drive (HDD).
[0070] The view finder 46 has a function of displaying images,
character information, and the like. The view finder 46 of this
embodiment is an electronic view finder (hereinafter, referred to
as "EVF"), and is used for displaying a live view image
(through-image) as an example of a continuous-frame image obtained
by imaging in continuous frames during imaging. The view finder 46
is also used for displaying a still image as an image of a
single-frame image obtained by imaging in a single frame in a case
where an instruction to capture a still image is provided. In
addition, the view finder 46 is also used for displaying a
reproduced image in a playback mode or displaying a menu screen or
the like.
[0071] The imaging optical system 40 comprises an imaging lens
including a focus lens, a motor, a slide mechanism, and a shutter
(all of these are not shown). The slide mechanism moves the focus
lens along the optical axis direction (not shown) of the imaging
optical system 40. The focus lens is attached so as to be slidable
along the optical axis direction of the slide mechanism. The motor
is connected to the slide mechanism, and the slide mechanism
receives power of the motor and slides the focus lens along the
optical axis direction. The motor is connected to the main control
unit 26 of the control unit 20, and is controlled and driven
according to a command from the main control unit 26. In the
distance measurement device 10 of this embodiment, as a specific
example of the motor, a stepping motor is applied. Accordingly, the
motor is operated in synchronization with pulse power in response
to a command from the main control unit 26.
[0072] In the distance measurement device 10 according to this
embodiment, in the auto-focus mode, the main control unit 26
performs focusing control by driving and controlling the motor of
the imaging optical system 40 such that a contrast value of an
image obtained by imaging with the imaging element 42 becomes the
maximum. Furthermore, in the auto-focus mode, the main control unit
26 calculates AE information which is a physical quantity
indicating brightness of an image obtained by imaging. The main
control unit 26 derives a shutter speed and an F-number (aperture
value) according to the brightness of the image indicated by the AE
information when the release button of the operating unit 44 is
brought into the half-pressing state. The main control unit 26
performs exposure adjustment by controlling respective related
units such that the derived shutter speed and F-number are
obtained.
[0073] The imaging element 42 is an imaging element comprising
color filters (not shown), and functions as an imaging unit
according to the technique of the present disclosure. In this
embodiment, as an example of the imaging element 42, a CMOS type
image sensor is used. The imaging element 42 is not limited to a
CMOS type image sensor, and may by, for example, a CCD image
sensor. The color filters include a G filter corresponding green
(G) most contributing to obtaining a brightness signal, an R filter
corresponding to red (R), and a B filter corresponding to blue (B).
Any filter of "R", "G", and "B" included in the color filters is
allocated to each of the pixels (not shown) of the imaging element
42.
[0074] In a case of imaging a subject, image light indicating the
subject is formed on the light receiving surface of the imaging
element 42 through the imaging optical system 40. The imaging
element 42 has a plurality of pixels (not shown) arranged in a
matrix in a horizontal direction and a vertical direction, and
signal charges according to image light are stored in the pixels of
the imaging element 42. The signal charges stored in the pixels of
the imaging element 42 are sequentially read as digital signals
according to the signal charges (voltages) under the control of the
main control unit 26. In the distance measurement device 10 of this
embodiment, the signal charges are sequentially read in units of
pixels for each horizontal direction, that is, for each pixel row.
In a period from when the electric charges are read from the pixels
of one pixel row until the electric charges are read from the
pixels of the next pixel row, a period (hereinafter, referred to as
a "horizontal blanking period") during which the signal charges are
not read is generated.
[0075] The imaging element 42 has a so-called electronic shutter
function, and operates the electronic shutter function to control
an electric charge storage time (shutter speed) of each photosensor
at a timing under the control of the main control unit 26.
[0076] The imaging element 42 outputs the digital signals
indicating the pixel values of the captured image from the
respective pixels. The captured image output from the respective
pixels is a chromatic image, and is, for example, a color image
having the same color arrangement as the pixel arrangement. The
captured image (frames) output from the imaging element 42 is
temporarily stored (overwritten and saved) in the storage unit of
the main control unit 26 or a RAW image storage area (not shown) of
the storage unit 48 determined in advance through the main control
unit 26.
[0077] The main control unit 26 subjects the frames to various
kinds of image processing. The main control unit 26 has a white
balance (WB) gain unit, a gamma correction unit, and a
synchronization processing unit (all of these are not shown), and
sequentially performs signal processing for the original digital
signals (RAW images) temporarily stored in the main control unit 26
or the like in each processing unit. That is, the WB gain unit
executes white balance (WB) adjustment by adjusting the gain of
each of R, G and B signals. The gamma correction unit performs
gamma correction of each of the R, G and B signals subjected to the
WB adjustment in the WB gain unit. The synchronization processing
unit performs color interpolation processing corresponding to the
arrangement of the color filters of the imaging element 42 and
generates the synchronized R, G and B signals. Each time the RAW
image for one screen is acquired by the imaging element 42, the
main control unit 26 performs image processing for the RAW image in
parallel.
[0078] The main control unit 26 outputs image data of the generated
captured image for recording to an encoder (not shown), which
converts an input signal to a signal in a different format. The R,
G and B signals processed by the main control unit 26 are converted
(encoded) to signals for recording by the encoder, and the signals
for recording are recorded in the storage unit 48. The captured
image for display processed by the main control unit 26 is output
to the view finder 46. Hereinafter, for convenience of description,
in a case where there is no need for distinction between the
"captured image for recording" and the "captured image for
display", the expression "for recording" and the expression "for
display" are omitted and the captured image for recording and the
captured image for display are referred to as "captured
images".
[0079] The main control unit 26 of this embodiment displays a live
view image on the view finder 46 by performing control for
continuously displaying the captured images for display as a motion
image.
[0080] The light emitting lens 30 and the laser diode 32 function
as an example of an emission unit according to the technique of the
present disclosure. The laser diode 32 is driven based on an
instruction from the distance measurement control unit 24 and has a
function of emitting a laser beam toward the subject to be a
measurement target through the light emitting lens 30 in the
optical axis direction of the imaging optical system 40. Specific
examples of the light emitting lens 30 of this embodiment include
an objective lens or the like. The laser beam emitted from the
laser diode 32 is an example of directional light according to the
technique of the present disclosure.
[0081] The light receiving lens 34 and the photodiode 36 function
as an example of a light receiving unit according to the technique
of the present disclosure. The photodiode 36 has a function of
receiving the laser beam emitted from the laser diode 32 and
reflected from the subject through the light receiving lens 34 and
outputting an electrical signal according to the amount of received
light to the distance measurement control unit 24.
[0082] If the user provides an instruction to measure (distance
measurement) a distance to a subject using the distance measurement
instruction button or the like of the operating unit 44, the main
control unit 26 instructs the distance measurement control unit 24
to perform a distance measurement. Specifically, in this
embodiment, the main control unit 26 instructs the distance
measurement control unit 24 to perform a distance measurement by
transmitting a distance measurement instruction signal to the
distance measurement control unit 24. In a case of performing a
measurement of a distance to a subject and imaging of the subject
in parallel, the main control unit 26 transmits a synchronization
signal for synchronizing a distance measurement operation and an
imaging operation to the distance measurement control unit 24.
[0083] If the synchronization signal and the distance measurement
instruction signal are received, the distance measurement control
unit 24 controls the light emission of the laser diode 32 at a
timing according to the count signal of the time counter 22 and
controls a timing of emitting a laser beam toward the subject. The
distance measurement control unit 24 samples the electric signal
according to the amount of received light output from the
photodiode 36 at the timing according to the count signal of the
time counter 22.
[0084] The distance measurement control unit 24 derives the
distance to the subject based on the light emission timing at which
the laser diode 32 emits a laser beam and the light reception
timing at which the photodiode 36 receives the laser beam, and
outputs distance data representing the derived distance to the main
control unit 26. The main control unit 26 displays information
relating to the distance to the subject on the view finder 46 based
on distance data. The main control unit 26 stores distance data in
the storage unit 48.
[0085] The measurement of the distance to the subject by the
distance measurement control unit 24 will be described in more
detail. FIG. 2 is a timing chart showing an example of a timing of
the distance measurement operation in the measurement of the
distance to the subject in the distance measurement device 10.
[0086] In the distance measurement device 10 of this embodiment, a
single distance measurement (measurement) sequence includes a
voltage adjustment period, an actual measurement period, and a
pause period. The voltage adjustment period refers to a period
during which a drive voltage of the laser diode 32 and the
photodiode 36 is adjusted to an appropriate voltage value. As a
specific example, in the distance measurement device 10 of this
embodiment, as shown in FIG. 2, the voltage adjustment period is
set to several 100 msec (milliseconds).
[0087] The actual measurement period refers to a period in which
the distance to the subject is actually measured. In the distance
measurement device 10 of this embodiment, as a specific example, as
shown in FIG. 2, the distance to the subject is measured by
repeating an operation to emit a laser beam and to receive the
laser beam reflected from the subject several 100 times and
measuring the elapsed time from light emission to light reception.
That is, in the distance measurement device 10 of this embodiment,
in the single measurement sequence, the measurement of the distance
to the subject is performed several 100 times.
[0088] FIG. 3 is an example of a timing chart showing a timing from
light emission to light reception in a single measurement. In a
case of performing a measurement, the distance measurement control
unit 24 outputs a laser trigger for causing the laser diode 32 to
emit light according to the count signal of the time counter 22 to
the laser diode 32. The laser diode 32 emits light according to the
laser trigger. In the distance measurement device 10 of this
embodiment, as a specific example, the light emission time of the
laser diode 32 is set to several 10 nsec (nanoseconds). The emitted
laser beam is emitted toward the subject through the light emitting
lens 30 in the optical axis direction of the imaging optical system
40. The laser beam emitted from the distance measurement device 10
is reflected from the subject and reaches the distance measurement
device 10. The photodiode 36 of the distance measurement device 10
receives the reflected laser beam through the light receiving lens
34.
[0089] In the distance measurement device 10 of this embodiment, as
a specific example, the distance measurement device performs a
distance measurement for a subject within 1 km from the distance
measurement device 10. The time until the laser beam emitted from
the laser diode 32 toward the subject 1 km ahead through the light
emitting lens 30 is returned (received) becomes 1 km.times.2/light
speed several.apprxeq..mu.sec (microseconds). Accordingly, in order
to measure the distance to the subject 1 km ahead, as shown in FIG.
2, the time of at least several .mu.sec is required.
[0090] In the distance measurement device 10 of this embodiment,
the reciprocation time or the like of the laser beam is considered,
and as a specific example, a single actual measurement time is set
to several msec as shown in FIG. 2. Since the reciprocation time of
the laser beam is different depending on the distance to the
subject, the actual measurement time for each time may be different
depending on the distance assumed by the distance measurement
device 10.
[0091] In the distance measurement device 10, the distance
measurement control unit 24 derives the distance to the subject
based on measured values obtained by performing a measurement
several 100 times as described above. In the distance measurement
control unit 24 of this embodiment, as a specific example, a
histogram of measured values for several 100 times is analyzed to
derive the distance to the subject. FIG. 4 is a graph showing an
example of a histogram of measured values in a case where the
distance to the subject is set as a horizontal axis and the
measurement frequency is set as a vertical axis. The distance
measurement control unit 24 derives the distance to the subject
corresponding to a maximum value of the measurement frequency in
the above-described histogram as a measurement result and outputs
distance data indicating the derived measurement result to the main
control unit 26. A histogram may be generated based on the
reciprocation time (the elapsed time from light emission to light
reception) of the laser beam or 1/2 of the reciprocation time of
the laser beam, or the like, instead of the distance to the
subject.
[0092] The pause period refers to a period for pausing the driving
of the laser diode 32 and the photodiode 36. In the distance
measurement device 10 of this embodiment, as a specific example, as
shown in FIG. 2, the pause period is set to several 100 msec.
[0093] In the distance measurement device 10 of this embodiment,
the single measurement time is set to several 100 msec.
[0094] In a case of not performing imaging, the main control unit
26 of the distance measurement device 10 of this embodiment
displays a live view image on the view finder 46 as described
above. The main control unit 26 performs the display of the live
view image by displaying the captured images captured in several 10
fps (several 10 msec/image) on the view finder 46 as a motion
image. For this reason, during the single measurement period, live
view images for measurement period/fps are displayed on the view
finder 46.
[0095] Next, the imaging operation and the distance measurement
operation in a case where the imaging operation and the distance
measurement operation in the distance measurement device 10 of this
embodiment are synchronized will be described. Hereinafter, as a
specific example, an imaging operation and a distance measurement
operation in a case where an imaging operation to capture a still
image and a distance measurement operation are synchronized will be
described.
[0096] First, control processing which is executed by the main
control unit 26 will be described. FIG. 5 is a flowchart showing an
example of a flow of control processing which is executed by the
main control unit 26 of the distance measurement device 10 of this
embodiment. FIG. 6 shows an example of a timing chart showing the
timings of the imaging operation and the distance measurement
operation. The flowchart shown in FIG. 5 is executed if power is
supplied to the distance measurement device 10.
[0097] First, in Step 100, the main control unit 26 starts a live
view operation. As described above, the main control unit 26
displays the live view image on the view finder 46 by performing
control for continuously displaying the captured images captured by
the imaging optical system 40 and the imaging element 42 as a
motion image.
[0098] Next, in Step 102, the main control unit 26 determines
whether or not to perform a distance measurement.
[0099] In the distance measurement device 10 of this embodiment, as
described above, shake correction of a so-called CCD shift system
is performed by the main control unit 26. For this reason, since
the imaging element 42 is moved, the position (image forming
position) of the subject image is also moved. In this way, if a
distance measurement is performed in a state where the position of
the subject image is moved, a distance measurement location (a
place where a laser beam is reflected) may be different from the
central position of the captured image. In this case, there is a
concern that distance measurement accuracy is degraded. For this
reason, in the distance measurement device 10 of this embodiment,
in a case where the distance measurement operation and the imaging
operation are performed in parallel, the main control unit 26
performs control such that shake correction is not performed.
[0100] Whether or not to perform a distance measurement is
determined according to whether or not the user instructs the
distance measurement through the operating unit 44, or the like. In
a case of not performing the distance measurement, the process
progresses to Step 136. In a case of not performing the distance
measurement, the above-described problem does not occur. For this
reason, the main control unit 26 performs shake correction. With
this, the main control unit 26 performs the imaging of the subject
while performing shake correction. After this step, the process
progresses to Step 138, and the imaging of the subject is performed
by the main control unit 26. In the imaging of this case, since the
distance measurement is not performed, a normal imaging operation
(normal imaging) may be performed. Specifically, though details
will be described below, the main control unit 26 performs the
processing of Steps 106 to 112 and Steps 116 to 120, and may store
the captured image (image data indicating the captured image) in
the storage unit 48.
[0101] In a case of performing the distance measurement, that is,
in a case of performing both of the imaging of the subject and the
distance measurement of the distance to the subject, the process
progresses to Step 104. In Step 104, shake correction is not
performed. With this, the main control unit 26 performs the imaging
of the subject without performing shake correction.
[0102] Next, in Step 106, the main control unit 26 determines
whether or not the release button of the operating unit 44 is
half-pressed. In a case where the release button is not
half-pressed, for example, in a case where the release button is
not pressed at all, or the like, the process progresses to Step
140. In a case where the release button is half-pressed, the
process progresses to Step 108.
[0103] In Step 108, the main control unit 26 controls the imaging
optical system 40 and performs AE and AF as described above. In the
distance measurement device 10, exposure adjustment is performed by
performing AE, focusing control is performed by performing AF, and
image light indicating the subject is formed on the light receiving
surface of the imaging element 42 in a focused state.
[0104] Next, in Step 110, the main control unit 26 determines
whether or not the release button of the operating unit 44 is fully
pressed. In a case where the release button is not fully pressed,
the process progresses to Step 110. In Step 110, the main control
unit 26 determines whether or not a pressing operation to the
release button of the operating unit 44 is released. In a case
where pressing is not released, the process returns to Step 108,
and this processing is repeated. In a case where pressing is
released, the process progresses to Step 140.
[0105] In a case where the release button is fully pressed, the
process progresses from Step 110 to Step 114. In Step 114, the main
control unit 26 transmits the synchronization signal to the
distance measurement control unit 24. In this way, in the distance
measurement device 10 of this embodiment, in order to synchronize
the imaging operation by the main control unit 26 with the distance
measurement operation by the distance measurement control unit 24,
prior to the start of the imaging (actual exposure to the imaging
element 42), the synchronization signal is transmitted from the
main control unit 26 to the distance measurement control unit 24.
Though details will be described below, in the distance measurement
control unit 24, if the synchronization signal is received, the
distance measurement operation (the measurement of the distance to
the subject) starts.
[0106] Next, in Step 116, the main control unit 26 starts the
actual exposure (imaging). With the start of the actual exposure,
the pixels of the imaging element 42 are irradiated with light
(image light is formed on the light receiving surface of the
imaging element 42), and signal charges according to irradiated
light are stored in the respective pixels.
[0107] Next, in Step 118, the main control unit 26 detects whether
or not the actual exposure ends. The process is in a standby state
until the actual exposure ends, and in a case where the actual
exposure ends, the process progresses to Step 120. A determination
method of whether or not the actual exposure ends is not limited,
and as a specific example, a determination method based on
determination of whether or not an actual exposure time determined
under various conditions has elapsed is used.
[0108] In Step 120, the main control unit 26 starts the reading of
the signal charges stored in the respective pixels of the imaging
element 42. Next, in Step 122, the main control unit 26 outputs a
reading start signal indicating the start of the reading to the
distance measurement control unit 24.
[0109] The signal charges read from the respective pixels are
transmitted to the main control unit 26 as electrical signals
(image signals), which are digital signals according to the signal
charges.
[0110] Next, in Step 124, the main control unit 26 determines
whether or not it is the horizontal blanking period. As described
above, in a case of reading the signal charges from the pixels of
the imaging element 42, since the signal charges are read in units
of pixels for each pixel row, the horizontal blanking period during
which the reading of the signal charges are not performed is
generated between the pixel rows. The main control unit 26
determines whether or not it is the horizontal blanking period, and
in a case where it is not the horizontal blanking period, for
example, while the signal charges are read from the pixels of one
pixel row, the process progresses to Step 128. In a case of the
horizontal blanking period, the process progresses to Step 126. In
Step 126, the main control unit 26 transmits a light emission
instruction signal to the distance measurement control unit 24.
Though details will be described below, if the light emission
instruction signal is received, the distance measurement control
unit 24 causes the laser diode 32 to emit light based on the
received light emission instruction signal.
[0111] Next, in Step 128, the main control unit 26 determines
whether or not to end the reading. In a case where the signal
charges are not yet read from all pixels of the imaging element 42,
the process returns to Step 124, and this processing is repeated.
In a case where the signal charges are read from all pixels of the
imaging element 42, the process progresses to Step 130.
[0112] In Step 130, the main control unit 26 transmits a reading
end signal indicating the end of the reading to the distance
measurement control unit 24.
[0113] Next, in Step 132, the main control unit 26 determines
whether or not distance data is received. Though details will be
described below, if the distance to the subject is measured
(distance measurement), the distance measurement control unit 24
transmits distance data indicating a measurement result to the main
control unit 26. The process is in a standby state until distance
data transmitted from the distance measurement control unit 24 is
received, and in a case where distance data is received, the
process progresses to Step 134.
[0114] In Step 134, the main control unit 26 displays information
relating to the distance to the subject on the view finder 46 based
on received distance data. The main control unit 26 stores received
distance data in the storage unit 48 in correlation with the
captured image. With this step, the captured image (image data
indicating the captured image) obtained by imaging the subject and
the distance (distance data) to the subject are stored in the
storage unit 48 in a state of being correlated with each other.
[0115] Next, in Step 140, the main control unit 26 determines
whether or not a power switch (not shown) is turned off. In a case
where the switch is not turned off, the process returns to Step
106, and this processing is repeated. In a case where the power
switch is turned off, the process progresses to Step 142.
[0116] In Step 142, the main control unit 26 stops the live view
operation, and then, ends this processing. The main control unit 26
turns off the power supply of the distance measurement device
10.
[0117] Next, distance measurement processing which is executed by
the distance measurement control unit 24 will be described. FIG. 7
is a flowchart showing an example of a flow of distance measurement
processing which is executed by the distance measurement control
unit 24 of the distance measurement device 10 of this
embodiment.
[0118] The flowchart shown in FIG. 7 is executed if power is
supplied to the distance measurement device 10.
[0119] First, in Step 200, the distance measurement control unit 24
determines whether or not the synchronization signal is received.
Specifically, the distance measurement control unit 24 determines
whether or not the synchronization signal transmitted from the main
control unit 26 in Step 114 of the control processing in the main
control unit 26 described above is received. The process is in a
standby state until the synchronization signal is received, and if
the synchronization signal is received, the process progresses to
Step 202.
[0120] In Step 202, the distance measurement control unit 24
transits to the voltage adjustment period shown in FIG. 6 and
performs voltage adjustment of the drive voltage of the laser diode
32 and the photodiode 36.
[0121] Next, in Step 204, the distance measurement control unit 24
determines whether or not the voltage adjustment ends. In this
embodiment, as described above and as shown in FIG. 6, the voltage
adjustment period is set to several 100 msec. For this reason, the
distance measurement control unit 24 determines that the voltage
adjustment ends in a case where several 100 msec have elapsed after
the transition to the voltage adjustment period. Accordingly, the
distance measurement control unit 24 determines that the voltage
adjustment does not end and is in a standby state until several 100
msec have elapsed after the transition to the voltage adjustment
period, and in a case where several 100 msec have elapsed,
determines that the voltage adjustment ends and progresses to Step
206.
[0122] In Step 206, the distance measurement control unit 24
transits to the actual measurement period and starts to measure the
distance to the subject.
[0123] Next, in Step 208, the distance measurement control unit 24
determines whether or not the reading start signal is received.
Specifically, the distance measurement control unit 24 determines
whether or not the reading start signal transmitted from the main
control unit 26 in Step 122 of the control processing in the main
control unit 26 described above is received.
[0124] For this reason, the distance measurement control unit 24 of
the distance measurement device 10 of this embodiment performs
control such that, in a reading period, the laser diode 32 emits
light in the above-described horizontal blanking period which is a
period during which the charge signals are not read from the
pixels. That is, the distance measurement control unit 24 performs
control such that, in the reading period, the laser diode 32 emits
light in synchronization with the imaging operation.
[0125] As described above, in a period out of the reading period,
since superimposition of noise due to variation in voltage does not
cause a problem, the laser diode 32 may not emit light in
synchronization with the imaging operation, and as described above,
the laser diode 32 may emit light every several msec according to
each measurement. Hereinafter, control by the distance measurement
control unit 24 in a period out of the reading period is referred
to as "normal control".
[0126] For this reason, in the distance measurement control unit 24
of the distance measurement device 10 of this embodiment, control
in the measurement of the distance to the subject is different
between the reading period and a period out of the reading
period.
[0127] In Step 208, since the distance measurement control unit 24
performs the normal control in a case where the reading start
signal is not received, the process progresses to Step 216. In a
case where the distance measurement control unit 24 receives the
reading start signal, the process progresses to Step 210.
[0128] In Step 210, the distance measurement control unit 24
determines whether or not the reading end signal is received.
[0129] Specifically, the distance measurement control unit 24
determines whether or not the reading end signal transmitted from
the main control unit 26 in Step 130 of the control processing in
the main control unit 26 described above is received.
[0130] Since the distance measurement control unit 24 performs the
normal control in a subsequent period in a case where the reading
end signal is received, the process progresses to Step 216. In a
case where the distance measurement control unit 24 does not
receive the reading end signal, the process progresses to Step
212.
[0131] In Step 212, the distance measurement control unit 24
determines whether or not the light emission instruction signal is
received. Specifically, the distance measurement control unit 24
determines whether or not the light emission instruction signal
transmitted from the main control unit 26 in Step 126 of the
control processing in the main control unit 26 described above is
received.
[0132] In a case where the distance measurement control unit 24
does not receive the light emission instruction signal, that is, in
a case where it is in the reading period and it is not yet in the
horizontal blanking period, the process is in the standby state. In
a case where the distance measurement control unit 24 receives the
light emission instruction signal, the process progresses to Step
214. In Step S214, it is determined whether or not the measurement
is being performed. In the distance measurement device 10 of this
embodiment, the interval (the reading time of the charge signals
from the pixels of one pixel row) between the horizontal blanking
periods is shorter than the single measurement time (in the
specific example described above, several msec). For this reason,
before the measurement ends, the next horizontal blanking period
may be reached, and the light emission instruction signal may be
transmitted from the main control unit 26 to the distance
measurement control unit 24. In the distance measurement control
unit 24 of this embodiment, in this way, in a case where the light
emission instruction signal is received during the measurement, the
received light emission instruction signal is neglected, whereby
the laser diode 32 does not emit light. For this reason, in a case
where the measurement is being performed, the process progresses to
Step 226. In a case where the measurement is not being performed,
the process progresses to Step 216.
[0133] In Step 216, the distance measurement control unit 24 causes
the laser diode 32 to emit light. Next, in Step 218, the distance
measurement control unit 24 determines whether or not a
predetermined time has elapsed. Specifically, as described above,
since the single measurement time is set to several msec, the
distance measurement control unit 24 determines whether or not
several msec have elapsed. In a case where the predetermined time
(in this embodiment, several msec which are the single measurement
time) has not elapsed, the process is in the standby state, and in
a case where the predetermined time has elapsed, the process
progresses to Step 220.
[0134] The laser diode 32 emits light through the processing of
Step 216, whereby the laser beam is emitted toward the subject
through the light emitting lens 30. The laser beam reflected from
the subject is received by the photodiode 36 through the light
receiving lens 34 until the predetermined time elapses. The
distance measurement control unit 24 acquires the elapsed time from
light emission to light reception in a case where the laser beam is
received by the photodiode 36 and stores the elapsed time in the
storage unit (for example, the RAM or the like in the distance
measurement control unit 24).
[0135] For example, in a case where the subject moves, or the like,
the elapsed time from light emission to light reception of the
laser beam exceeds several msec which are the actual measurement
time per measurement, and the laser beam may not be returned
(reflected light may not be received). In this case, a measurement
error occurs. In a case where a measurement error occurs, the
distance measurement control unit 24 stores the effect in the
storage unit (for example, the RAM or the like in the distance
measurement control unit 24), and the occurrence of the measurement
error may be displayed on the view finder 46 or the like according
to the frequency of the occurrence of the measurement error, for
example, if the frequency is not negligible in deriving the
distance to the subject using a histogram. In this way, in a case
where a measurement error occurs, the main control unit 26 may not
store the captured image in the storage unit 48. In this case, the
user can set whether or not to store the captured image through the
operating unit 44 (an example of a storage setting unit according
to the technique of the present disclosure).
[0136] Next, in Step 220, the distance measurement control unit 24
determines whether or not a predetermined number of measurements
end. In a case where a predetermined number of measurements do not
end, the process returns to Step 208, and the measurement is
repeated. In a case where a predetermined number of measurements
end, the process progresses to Step 222.
[0137] In Step 222, the distance to the subject is derived based on
the time from when the photodiode 36 emits the laser beam through
the processing of Step 216 until the photodiode 36 receives the
laser beam. As an example, as shown in FIG. 4, the distance
measurement control unit 24 generates a histogram of the distance
to the subject and derives the distance to the subject
corresponding to a maximum value of the measurement frequency from
the histogram as a measurement result. In a case where a histogram
relating to the time, such as the reciprocation time of the laser
beam, is generated, first, the time corresponding to the maximum
value of the measurement frequency may be derived, and the distance
to the subject may be derived based on the derived time. For
example, in a case of a histogram relating to the reciprocation
time of the laser beam, the distance to the subject may be derived
by 1/2 of the reciprocation time of the laser beam corresponding to
the maximum value of the measurement frequency.times.the light
speed.
[0138] Next, in Step 224, the distance measurement control unit 24
transmits distance data indicating the distance derived in Step 222
to the main control unit 26, and then, the process progresses to
Step 226.
[0139] In Step 226, the distance measurement control unit 24
determines whether or not to end this distance measurement
processing. In a case where end conditions determined in advance
are satisfied, for example, in a case where the main control unit
26 determines that the power switch is turned off, this distance
measurement processing ends. In a case where the end conditions are
not satisfied, the process returns to Step 200, and this distance
measurement processing is repeated.
[0140] As described above, in the distance measurement device 10 of
this embodiment, in a case of performing the imaging operation and
the distance measurement operation in parallel, the main control
unit 26 performs control such that shake correction is not
performed. In a case of performing only the imaging operation,
control is performed such that shake correction is performed.
[0141] In this way, since the main control unit 26 of the distance
measurement device 10 of this embodiment does not perform shake
correction during the distance measurement, the central position of
the image formed on the imaging element 42 is not deviated from the
irradiation position of the laser beam emitted by the laser diode
32. Therefore, according to the distance measurement device 10 of
this embodiment, it is possible to suppress degradation of distance
measurement accuracy due to shake correction.
[0142] In this embodiment, although a case where, in a case of
performing the imaging operation and the distance measurement
operation in parallel, the main control unit 26 performs control
such that shake correction is not performed has been described, the
invention is not limited thereto, and a shake correction amount may
be smaller than that in a case of performing normal imaging. A
flowchart illustrating control processing in this case is shown in
FIG. 8. In the control processing in this case, Step 103 may be
provided instead of Step 104 of the control processing shown in
FIG. 5, and Step 137 may be provided instead of Step 136. In FIG.
8, subsequent processing is the same as in the control processing
shown in FIG. 5, and thus, description thereof will not be
repeated.
[0143] In the control processing shown in FIG. 8, the main control
unit 26 progresses to Step 137 in a case of not performing the
distance measurement, performs shake correction with a shake
correction amount A, and then, progresses to Step 138 to perform
normal imaging. The shake correction amount A is a shake correction
amount in a case of performing normal imaging, and is a correction
amount for appropriately capturing an image of the subject.
[0144] The main control unit 26 progresses to Step 103 in a case of
performing the distance measurement, performs shake correction with
a shake correction amount B, and then, progresses to Step 106 to
perform the imaging operation in parallel with the distance
measurement operation. The shake correction amount B is a
correction amount smaller than the shake correction amount A. The
correction amount B may be determined according to degradation of
distance measurement accuracy and image quality of the captured
image, and may be determined, for example, by an experiment or the
like in advance taking into consideration the influence on distance
measurement accuracy.
[0145] In a case of performing shake correction during the distance
measurement operation, as described above, the irradiation position
of the laser beam moves. For this reason, the irradiation position
may be displayed on the view finder 46. A flowchart illustrating
control processing in this case is shown in FIG. 9. In the control
processing shown in FIG. 9, Step 105 is provided between Steps 103
and 106 of the control processing shown in FIG. 8. In a case of
performing a main imaging operation and the distance measurement
operation in parallel, the main control unit 26 sets the shake
correction amount to the shake correction amount B, and then, in
Step 105, displays a marker representing the irradiation position
on a live view image displayed on the view finder 46 in a
superimposed manner. FIGS. 10A to 10C show a display example of a
marker 90. As shown in FIG. 10A, the marker 90 is displayed on a
live view image displayed on the view finder 46 in a superimposed
manner. The size of the marker 90 may be different depending on a
shake amount. The main control unit 26 computes a shake amount
based on a detection result of the shake detection unit 43, in a
case where the shake amount is large, as shown in FIG. 10B,
displays the marker 90 large, and in a case where the shake amount
is small, as shown in FIG. 10C, displays the marker 90 small.
[0146] In this embodiment, although an imaging operation in a case
of capturing a still image has been described, even in a case of
capturing a motion image, as in this embodiment, the main control
unit 26 may control shake correction. In a case of displaying a
live view image, and in a case of performing shake correction, as
in this embodiment, the main control unit 26 may control shake
correction regardless of the imaging operation.
[0147] In this embodiment, although the distance measurement
control unit 24 performs control such that the laser diode 32 emits
light in the horizontal blanking period, a timing at which the
laser diode 32 emits light may be a period during which the degree
of influence on the reading state of the image signal is equal to
or less than an allowable degree determined in advance. When the
degree of influence is the allowable degree determined in advance,
for example, there is a case where image disruption to the extent
of causing no problem (being unnoticeable) in a case where the user
visually recognizes the captured image is set within an allowable
range, or the like. The laser diode 32 may emit light in a period
(a so-called vertical blanking period or the like) during which the
charges are not read between the frames in reading the charges, not
in the horizontal blanking period.
[0148] As a method of synchronizing the distance measurement
operation by the distance measurement control unit 24 with the
imaging operation by the main control unit 26, a clock signal of
the time counter 22 may be controlled using the main control unit
26.
[0149] In this embodiment, although an example where the distance
measurement control unit 24 derives the distance to the subject by
performing a measurement using the emission and reception of the
laser beam multiple times (for example, several 100 times) has been
described, a focus adjustment result may be used when deriving the
distance. For example, when analyzing the histogram (FIG. 4)
generated from a plurality of measurement results using the
emission and reception of the laser beam, the distance range (the
range of the subject distance and the vicinity thereof) of the
distance to the subject is understood from the AF result.
Accordingly, as shown in FIG. 11A, the distance to the subject may
be derived only using the measurement results within the subject
distance range based on AF without using the measurement results
(hatched portions in FIG. 11A) outside the subject distance range
based on AF. With this, if the distance range is determined, since
a resolution is uniquely determined, it is possible to increase the
resolution of the distance range when determining the frequency
compared to using all measured values, and to derive the distance
to the subject in units of minute numerical values. In the example
of FIG. 11A, although an example in which the measured values of
the distances shorter and the distances longer than the subject
distance range based on AF are not used together has been shown,
either of them may not be used. That is, the distance to the
subject may be derived without using the measured values (a hatched
portion in FIG. 11B) of the distances less than the subject
distance based on AF or the measured values (a hatched portion in
FIG. 11C) of the distances longer than the subject distance based
on AF. Furthermore, a result of manual focus adjustment in the
manual focus mode may be used instead of AF.
[0150] In this embodiment, in a case where the distance measurement
control unit 24 performs the distance measurement, as shown in FIG.
12, the focusing state specification information specifying the AF
result (or the manual focus adjustment result) or the exposure
state specification information specifying the AE result is
acquired from the main control unit 26, and at least one of the
laser diode 32 or the photodiode 36 may be driven and adjusted
based on the acquired focusing state specification information and
exposure state specification information. That is, since an
approximate distance to the subject is understood from the focus
adjustment result (focal distance), the emission intensity of the
laser beam emitted from the laser diode 32 may be adjusted based on
the focusing state specification information specifying the AF
result. For example, the shorter the focal distance, the lower the
emission intensity is set. With this, while ambient light becomes
noise, it is possible to derive the distance to the subject with
proper emission intensity of the laser beam without being affected
by noise of ambient light. Similarly, since an approximate distance
to the subject is understood from the focus adjustment result, the
light receiving sensitivity of the photodiode 36 may be adjusted
based on the focusing state specification information specifying
the AF result. For example, the shorter the focal distance, the
lower the light receiving sensitivity is set. With this, it is
possible to derive the distance to the subject with proper light
receiving sensitivity without being affected by noise of ambient
light. Alternatively, since necessary intensity of the laser beam
is understood from the exposure adjustment result, the emission
intensity of the laser beam may be adjusted based on the exposure
state specification information specifying the AE result. For
example, the higher the exposure, the lower the emission intensity
is set. Alternatively, since high exposure means that subject
brightness becomes low, the lower the subject brightness, the lower
the emission intensity may be set. With this, it is possible to
derive the distance to the subject with proper emission intensity
of the laser beam without being affected by noise of ambient
light.
[0151] In this embodiment, although a case where the distance
measurement device 10 captures a still image has been described,
even in a case of capturing a motion image, the main control unit
26 may perform control as described above. In capturing a motion
image, a measurement (measurement sequence) may be repeatedly
performed. Furthermore, a still image may be repeatedly captured
during a single measurement.
[0152] In this embodiment, although a case where voltage adjustment
is performed simultaneously with the distance measurement start
timing and the actual exposure start timing has been illustrated,
the technique of the present disclosure is not limited thereto. For
example, as shown in FIG. 13, prior to the start of the distance
measurement and the start of the actual exposure, as a specific
example, the voltage adjustment may be performed in a period during
which a live view image is displayed, or the like. In this case,
for example, in the distance measurement processing by the distance
measurement control unit 24 shown in FIG. 7, the processing of
Steps 202 and 204 may be performed prior to Step 200. Furthermore,
the voltage adjustment may not be performed.
[0153] In the above-described embodiment, although a case where
information relating to the distance to the subject is displayed on
the view finder 46 so as to be superimposed on a live view image
has been illustrated, the technique of the present disclosure is
not limited thereto. For example, information relating to the
distance to the subject may be displayed in a display area
different from the display area of the live view image. In this
way, information relating to the distance to the subject may be
displayed on the view finder 46 in parallel with the display of the
live view image.
[0154] In the above-described embodiment, for convenience of
description, although description has been provided on an
assumption that there is no AF error, the technique of the present
disclosure is not limited thereto. That is, the distance
measurement control unit 24 may derive the distance as described
above in a case where an AF error does not occur, and may not
derive the distance in a case where an AF error occurs.
[0155] In the above-described embodiment, for convenience of
description, although description has been provided on an
assumption that there is no AE error, the technique of the present
disclosure is not limited thereto. That is, the distance
measurement control unit 24 may derive the distance as described
above in a case where an AE error does not occur, and may not
derive the distance in a case where an AE error occurs.
[0156] In the above-described embodiment, although the focus
adjustment and the exposure adjustment by AF and AE have been
illustrated, the technique of the present disclosure is not limited
thereto, focus adjustment by manual focus and exposure adjustment
by manual exposure may be applied.
[0157] In the above-described embodiment, although a case where the
release button provided in the distance measurement device 10 is
operated has been illustrated, the technique of the present
disclosure is not limited thereto. For example, AE and AF may be
started in response to an imaging preparation instruction received
by a user interface (UI) unit of an external device used in the
form of being connected to the distance measurement device 10, and
actual exposure may be started in response to an imaging instructed
received by the UI unit of the external device. Examples of the
external device used in the form of being connected to the distance
measurement device 10 include a smart device, a personal computer
(PC), or a spectacles type or a wristwatch type wearable terminal
device.
[0158] In the above-described embodiment, although a case where the
live view image and the distance measurement result (information
relating to the distance to the subject) are displayed on the view
finder 46 has been illustrated, the technique of the present
disclosure is not limited thereto. For example, at least one of the
live view image or the distance measurement result may be displayed
on a display unit of the external device used in the form of being
connected to the distance measurement device 10. Examples of the
display unit of the external device used in the form of being
connected to the distance measurement device 10 include a display
of a smart device, a display of a PC, or a display of a wearable
terminal device.
[0159] The control processing (see FIG. 5) and the distance
measurement processing (see FIGS. 5A and 5B) described in the
above-described embodiment are merely examples. Accordingly, it is
needless to say that unnecessary steps may be deleted, new steps
may be added, or the processing order may be rearranged without
departing the gist of the invention. The respective processing
included in the control processing and the distance measurement
processing described in the above-described embodiment may be
realized by a software configuration using a computer by executing
a program, or may be realized by other hardware configurations.
Furthermore, the respective processing may be realized by a
combination of a hardware configuration and a software
configuration.
[0160] Furthermore, it is needless to say that the technique of the
present disclosure can also be applied to a digital camera.
[0161] In the above-described embodiment, although a case where the
light emission frequency of the laser beam is fixed has been
illustrated, the technique of the present disclosure is not limited
thereto. Since ambient light becomes noise for the laser beam, the
light emission frequency of the laser beam may be a light emission
frequency determined according to subject brightness.
[0162] Hereinafter, an example of a way of determining the light
emission frequency of the laser beam will be described.
[0163] The light emission frequency of the laser beam is derived
from a light emission frequency determination table 300 shown in
FIG. 14 as an example. In the light emission frequency
determination table 300, the subject brightness and the light
emission frequency of the laser beam are correlated with each other
such that the higher the subject brightness, the larger the light
emission frequency of the laser beam becomes. That is, in the light
emission frequency determination table 300, the subject brightness
has a magnitude relationship of L.sub.1<L.sub.2< . . .
<L.sub.n, and the light emission frequency has a magnitude
relationship of N.sub.1<N.sub.2< . . . <N.sub.n. In the
example shown in FIG. 2, although the light emission frequency in
units of 100 times has been illustrated, the invention is not
limited thereto, and the light emission frequency may be determined
in units of ten times or once by the light emission frequency
determination table 300.
[0164] In the distance measurement device 10, in order to realize
the derivation of the light emission frequency of the laser beam by
the light emission frequency determination table 300, brightness
information transmission processing (see FIG. 15) is executed by
the main control unit 26, and light emission frequency
determination processing (see FIG. 16) is executed by the distance
measurement control unit 24.
[0165] First, the brightness information transmission processing
which is executed by the main control unit 26 if the power switch
of the distance measurement device 10 is turned on will be
described referring to FIG. 15.
[0166] In the brightness information transmission processing shown
in FIG. 15, first, in Step 400, the main control unit 26 determines
whether or not brightness acquisition start conditions which are
conditions for starting acquisition of subject brightness are
satisfied. An example of the brightness acquisition start
conditions is a condition that the release button is half-pressed.
Another example of the brightness acquisition start conditions is a
condition that the captured image is output from the imaging
element 42.
[0167] In Step 400, in a case where the brightness acquisition
start conditions are satisfied, the determination is affirmative,
and the process progresses to Step 402. In Step 400, in a case
where the brightness acquisition start conditions are not
satisfied, the determination is negative, and the process
progresses to Step 406.
[0168] In Step 402, the main control unit 26 acquires the subject
brightness from the captured image, and then, the process
progresses to Step 404. Here, although a case where the subject
brightness is acquired from the captured image has been
illustrated, the technique of the present disclosure is not limited
thereto. For example, if a brightness sensor which detects subject
brightness is mounted in the distance measurement device 10, the
main control unit 26 may acquire the subject brightness from the
brightness sensor.
[0169] In Step 404, the main control unit 26 transmits brightness
information indicating the subject brightness acquired in Step 402
to the distance measurement control unit 24, and then, the process
progresses to Step 406.
[0170] In Step 406, the main control unit 26 determines whether or
not end conditions which are conditions for ending this brightness
information transmission processing are satisfied. An example of
the end conditions is a condition that the power switch of the
distance measurement device 10 is turned off. In Step 406, in a
case where the end conditions are not satisfied, the determination
is negative, and the process progresses to Step 400. In Step 406,
in a case where the end conditions are satisfied, the determination
is affirmative, and this brightness information transmission
processing ends.
[0171] Next, the light emission frequency determination processing
which is executed by the distance measurement control unit 24 if
the power switch of the distance measurement device 10 is turned on
will be described referring to FIG. 16.
[0172] In the light emission frequency determination processing
shown in FIG. 16, first, in Step 410, the distance measurement
control unit 24 determines whether or not the brightness
information transmitted by executing the processing of Step 404 is
received. In Step 410, in a case where the brightness information
transmitted by executing the processing of Step 404 is not
received, the determination is negative, and the process progresses
to Step 416. In Step 410, in a case where the brightness
information transmitted by executing the processing of Step 404 is
received, the determination is affirmative, and the process
progresses to Step 412.
[0173] In Step 412, the distance measurement control unit 24
derives the light emission frequency corresponding to the subject
brightness indicated by the brightness information received in Step
410 from the light emission frequency determination table 300, and
then, the process progresses to Step 414.
[0174] In Step 414, the distance measurement control unit 24 stores
the light emission frequency derived in the processing of Step 412
in the storage unit 48, and then, the process progresses to Step
416. The light emission frequency stored in the storage unit 48 by
the processing of Step 416 means "a predetermined number of times"
in Step 220 of the distance measurement processing shown in FIG.
7.
[0175] In Step 416, the main control unit 26 determines whether or
not end conditions which are conditions for ending this light
emission frequency determination processing are satisfied. An
example of the end conditions is a condition that the power switch
of the distance measurement device 10 is turned off. In Step 416,
in a case where the end conditions are not satisfied, the
determination is negative, and the process progresses to Step 410.
In Step 416, in a case where the end conditions are satisfied, the
determination is affirmative, and this light emission frequency
determination processing ends.
[0176] Next, another example of a way of determining the light
emission frequency of the laser beam will be described.
[0177] As an example, the light emission frequency of the laser
beam is derived according to a light emission frequency
determination table 500 shown in FIG. 17. In the light emission
frequency determination table 500, exposure state specification
information (E.sub.1, E.sub.2, . . . , E.sub.n) uniquely determined
according to the subject brightness and the light emission
frequency (N.sub.1, N.sub.2, . . . N.sub.n) of the laser beam are
correlated with each other. Here, the exposure state specification
information uniquely determined according to the subject brightness
means, for example, exposure state specification information
indicating that, the higher the subject brightness, the lower the
exposure becomes.
[0178] In a case of deriving the light emission frequency of the
laser beam using the light emission frequency determination table
500, exposure state specification information transmission
processing (see FIG. 18) is executed by the main control unit 26,
and light emission frequency determination processing (see FIG. 19)
is executed by the distance measurement control unit 24.
[0179] First, the exposure state specification information
transmission processing which is executed by the main control unit
26 if the power switch of the distance measurement device 10 is
turned on will be described referring to FIG. 18.
[0180] In the exposure state specification information transmission
processing shown in FIG. 18, first, in Step 600, the main control
unit 26 determines whether or not the release button is
half-pressed. In Step 600, in a case where the release button is
not half-pressed, the determination is negative, and the process
progresses to Step 606. In Step 600, in a case where the release
button is half-pressed, the determination is affirmative, and the
process progresses to Step 602. In FIG. 18, although a case where
the operating unit 44 comprises the release button has been
described as an example, the technique of the present disclosure is
not limited thereto. For example, in a case where the operating
unit 44 comprises a distance measurement imaging start button, Step
600 may be omitted, and in a case where power is supplied, the
processing of Step 602 may be started.
[0181] In Step 602, the main control unit 26 performs AE based on
the subject brightness acquired from the captured image, and then,
the process progresses to Step 604.
[0182] In Step 604, the main control unit 26 transmits the exposure
state specification information to the distance measurement control
unit 24, and then, the process progresses to Step 606.
[0183] In Step 606, the main control unit 26 determines whether or
not end conditions which are conditions for ending this exposure
state specification information transmission processing are
satisfied. An example of the end conditions is a condition that the
power switch of the distance measurement device 10 is turned off.
In Step 606, in a case where the end conditions are not satisfied,
the determination is negative, and the process progresses to Step
600. In Step 606, in a case where the end conditions are satisfied,
the determination is affirmative, and this exposure state
specification information transmission processing ends.
[0184] Next, the light emission frequency determination processing
which is executed by the distance measurement control unit 24 if
the power switch of the distance measurement device 10 is turned on
will be described referring to FIG. 19.
[0185] In the light emission frequency determination processing
shown in FIG. 19, first, in Step 610, the distance measurement
control unit 24 determines whether or not the exposure state
specification information transmitted by executing the processing
of Step 604 is received. In Step 610, in a case where the exposure
state specification information transmitted by executing the
processing of Step 604 is not received, the determination is
negative, and the process progresses to Step 616. In Step 610, in a
case where the exposure state specification information transmitted
by the executing the processing of Step 604 is received, the
determination is affirmative, and the process progresses to Step
612.
[0186] In Step 612, the distance measurement control unit 24
derives the light emission frequency corresponding to the exposure
state specification information received in Step 610 from the light
emission frequency determination table 500, and then, the process
progresses to Step 614.
[0187] In Step 614, the distance measurement control unit 24 stores
the light emission frequency derived in the processing of Step 612
in the storage unit 48, and then, the process progresses to Step
616. The light emission frequency stored in the storage unit 48 by
the processing of Step 616 means "a predetermined number of times"
in Step 220 of the distance measurement processing shown in FIG.
7.
[0188] In Step 616, the main control unit 26 determines whether or
not end conditions which are conditions for ending this exposure
state specification information transmission processing are
satisfied. An example of the end conditions is a condition that the
power switch of the distance measurement device 10 is turned off.
In Step 616, in a case where the end conditions are not satisfied,
the determination is negative, and the process progresses to Step
610. In Step 616, in a case where the end conditions are satisfied,
the determination is affirmative, and this exposure state
specification information transmission processing ends.
[0189] In this way, since the distance measurement device 10 makes
the light emission frequency (distance measurement frequency) of
the laser beam larger when the subject brightness is higher, it is
possible to obtain a distance measurement result, in which the
influence of noise of ambient light is moderated, compared to a
case where the light emission frequency (distance measurement
frequency) of the laser beam is fixed regardless of the subject
brightness.
[0190] In the above-described embodiment, although the laser beam
has been illustrated as light for distance measurement, the
technique of the present disclosure is not limited thereto, and
directional light which is light having directivity may be used.
For example, directional light which is obtained by a light
emitting diode (LED) or a super luminescent diode (SLD) may be
used. The directivity of directional light is preferably the same
directivity as the directivity of the laser beam, and is
preferably, for example, the directivity usable in a distance
measurement within a range of several meters to several
kilometers.
[0191] The disclosures of Japanese Patent Application No.
2014-095556 filed on May 2, 2014 and Japanese Patent Application
No. 2014-159806 filed on Aug. 5, 2014 are incorporated by reference
in this specification.
[0192] All documents, patent applications, and technical
specifications described in this specification are incorporated by
reference in this specification as if each of the documents, the
patent applications, and the technical specification is concretely
and respectively specified as being incorporated by reference
herein.
[0193] In regard to the above embodiment, the following appendixes
are further disclosed.
[0194] (Appendix 1)
[0195] A distance measurement device comprising an imaging optical
system which forms a subject image indicating a subject, an imaging
unit which captures the subject image formed by the imaging optical
system, an emission unit which emits a laser beam along an optical
axis direction of the imaging optical system, a light receiving
unit which receives reflected light of the laser beam from the
subject, a derivation unit which performs a distance measurement to
derive a distance to the subject based on a timing at which the
laser beam is emitted by the emission unit and a timing at which
the reflected light is received by the light receiving unit, a
camera shake correction unit which performs camera shake
correction, and a control unit which performs control such that the
camera shake correction unit does not perform the camera shake
correction or performs the camera shake correction with a
correction amount smaller than a normal correction amount
determined in advance in a case of performing the distance
measurement and performs the camera shake correction with the
normal correction amount in a case of not performing the distance
measurement.
[0196] (Appendix 2)
[0197] A distance measurement method comprising performing a
distance measurement to derive a distance to a subject based on a
timing at which a laser beam is emitted by an emission unit
emitting the laser beam along an optical axis direction of an
imaging optical system forming a subject image indicating the
subject and a timing at which reflected light is received by a
light receiving unit receiving the reflected light of the laser
beam from the subject, and performing control such that a camera
shake correction unit does not perform camera shake correction or
performs the camera shake correction with a correction amount
smaller than a normal correction amount determined in advance in a
case of performing the distance measurement and performs the camera
shake correction with the normal correction amount in a case of not
performing the distance measurement.
[0198] (Appendix 3)
[0199] A distance measurement program which causes a computer to
execute processing including performing a distance measurement to
derive a distance to a subject based on a timing at which a laser
beam is emitted by an emission unit emitting the laser beam along
an optical axis direction of an imaging optical system forming a
subject image indicating the subject and a timing at which
reflected light is received by a light receiving unit receiving the
reflected light of the laser beam from the subject, and performing
control such that a camera shake correction unit does not perform
camera shake correction or performs the camera shake correction
with a correction amount smaller than a normal correction amount
determined in advance in a case of performing the distance
measurement and performs the camera shake correction with the
normal correction amount in a case of not performing the distance
measurement.
* * * * *